When you create a deployment on the Elasticsearch Service, a master node and
two data nodes are provisioned automatically. By installing from the tar or zip
archive, you can start multiple instances of Elasticsearch locally to see how a multi-node
cluster behaves.

The additional nodes are assigned unique IDs. Because you’re running all three
nodes locally, they automatically join the cluster with the first node.

Use the cat health API to verify that your three-node cluster is up running.
The cat APIs return information about your cluster and indices in a
format that’s easier to read than raw JSON.

You can interact directly with your cluster by submitting HTTP requests to
the Elasticsearch REST API. Most of the examples in this guide enable you to copy the
appropriate cURL command and submit the request to your local Elasticsearch instance from
the command line. If you have Kibana installed and running, you can also
open Kibana and submit requests through the Dev Console.

The cluster status will remain yellow if you are only running a single
instance of Elasticsearch. A single node cluster is fully functional, but data
cannot be replicated to another node to provide resiliency. Replica shards must
be available for the cluster status to be green. If the cluster status is red,
some data is unavailable.

Installing Elasticsearch from an archive file enables you to easily install and run
multiple instances locally so you can try things out. To run a single instance,
you can run Elasticsearch in a Docker container, install Elasticsearch using the DEB or RPM
packages on Linux, install using Homebrew on macOS, or install using the MSI
package installer on Windows. See Installing Elasticsearch for more information.